Highly Selective Protic-Solvent-Mediated Organic-Inorganic Hybrid Cuprous Bromides Achieving Structural Transformation.

The potential application of stimuli-responsive hybrid copper halides in information storage and switch devices has generated significant interest. However, their transformation mechanism needs to be further studied deeply. Herein, two zero-dimensional (0D) organic-inorganic hybrids, namely, (TBA)CuBr 2 ( 1 ) with linear [CuBr 2 ] - units and (TBA) 2 Cu 4 Br 6 ( 2 ) with [Cu 4 Br 6 ] 2- clusters (TBA + = (C 4 H 9 ) 4 N + ), are synthesized using simple solvent evaporation approaches. Interestingly, upon exposure to distinct protic solvents, such as methanol, ethanol, ethylene glycol, or hot water, 1 undergoes a transformation into 2 with varying degrees of transition, accompanied by a change in luminescence color from cyan to orange (or mixed color) under high-energy emission (e.g., 254 nm) excitation. Hot water can trigger 1 to completely transform into 2 because of its large contact angle difference in the solvents. Furthermore, 2 can be converted back to 1 through a simple solid-state mechanochemical reaction. Additionally, the structure of 2 remains unchanged even after immersion in 80 °C H 2 O for 168 h due to the dense organic framework. This study provides valuable insights for exploring reversible structural transformation materials in the 0D metal halide system.